#define  _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <math.h>
int main()
{
	double a1, a2, b1, b2, c1, c2;
	scanf("%lf%lf%lf%lf%lf%lf", &a1, &a2, &b1, &b2, &c1, &c2);
	double dis1 = sqrt((a1 - b1) * (a1 - b1) + (a2 - b2) * (a2 - b2));
	double dis2 = sqrt((a1 - c1) * (a1 - c1) + (a2 - c2) * (a2 - c2));
	double dis3 = sqrt((c1 - b1) * (c1 - b1) + (c2 - b2) * (c2 - b2));
	printf("%.2lf", dis1 + dis2 + dis3);

	return 0;
}